The Illyrians were Indo-European tribesmen who appeared in the western portion of the Balkan Peninsula about 1000 B.C., a period coinciding with the end of the Bronze Age and beginning of the Iron Age. They inhabited much of the area for at least the next millennium. Archaeologists associate the Illyrians with the Hallstatt culture, an Iron Age people noted for production of iron, bronze swords with winged-shaped handles, and domestication of horses. The Illyrians occupied lands extending from the Danube, Sava, and Morava rivers to the Adriatic Sea and the Sar Mountains. At various times, groups of Illyrians, such as the Messapians and Iapyges, migrated to Italy through both overland routes and the sea.
Albanians were originally an extension of the southeast Illyrian peoples. By contrast with other areas, the coastal hinterland between the Narenta and the Drilon was occupied by a considerable number of smaller tribes, most of whom lost their identities during the final stages of Roman occupation. The twenty peoples listed by Pliny were only a fraction of the eighty-nine civitates attested by Varro a century earlier at the Narona conventus.
The southeast of Dalmatia was populated by "real Illyrians," and the evidence from personal names produces a uniform picture with very little influence from other parts of the province, except for a group of Celtic names in the upper Neretva valley around Konjic. In the later 3rd and 2nd centuries B.C., all these peoples were part of the Illyrian kingdom, but with the removal of King Genti they all attained some form of independence, mostly through treaty arrangements with the Romans.
The Illyrians carried on commerce and warfare with their neighbors: Greeks, Paionians, Thracians, and other peoples. To the east in Dardania, there was a broad area of intermingling, or a "contact zone," between Illyrians and Thracians. This area encompassed the Danube below Belgrade down the west of the Morava valley to the Vardar and the northern border of Macedonia. In the south and along the Adriatic Sea coast, the Illyrians were heavily influenced by the Greeks, who founded trading colonies there. At the end of the 7th century B.C., Corinthian Greek settlers from Corfu established ports on the coast at Apollonia (Pojanë, near modern Vlorë) in 588 B.C. and farther north at Lissos (Lezhë) and Epidamnos (modern Durrës) in 623 B.C. The Illyrians living in Albania's rugged mountains, however, resisted Greek settlement. Illyrian raiders attacked the coastal cities and Illyrian pirates threatened Greek trading ships in the Adriatic Sea.
Illyrians produced and traded cattle, horses, agricultural goods, and wares fashioned from locally mined copper and iron. Feuds and warfare were constant facts of life for the Illyrian tribes, and Illyrian pirates plagued shipping on the Adriatic Sea. Councils of elders (bulae) chose the chieftains who headed each of the numerous Illyrian tribes. From time to time, local chieftains extended their rule over other tribes and formed short-lived kingdoms. During the fifth century B.C., well-developed Illyrian population centers existed as far north as the upper Sava River valley in what is now Slovenia. Illyrian friezes discovered near the present-day Slovenian city of Ljubljana depict ritual sacrifices, feasts, battles, sporting events, and other activities.
The Illyrian kingdom of Bardhyllis became a formidable local power in the fourth century B.C. He fought against Greek settlers and Macedonia, a powerful kingdom to the southeast. In 358 B.C., however, Macedonia's Phillip II, father of Alexander the Great, defeated the Illyrians and assumed control of their territory as far as Lake Ohrid. Alexander himself routed the forces of the Illyrian chieftain Clitus in 335 B.C. and Illyrian tribal leaders and soldiers accompanied Alexander on his conquest of Persia. After Alexander's death in 323 B.C., new Illyrian kingdoms were established. In 312 B.C., King Glaucius expelled the Greeks from Durrës. By the end of the third century, the Illyrian king Agron had united many independent cities and greatly expanded Illyrian territory. Agron made Shkodër his capital and built an army and navy to protect Illyrian cities and ports. His kingdom, which stretched from Dalmatia in the north to the Vijosë River in the south, controlled parts of northern Albania, Montenegro, and Hercegovina. After Agron's death in 231 B.C., control of Illyria passed to his widow, Teuta. The queen ordered several attacks on neighboring states, but the pirate raids on merchant vessels in the Adriatic Sea made Teuta's realm an enemy of Rome. Roman troops defeated Teuta's army and seized the port of Epidamnos, which the Romans renamed Durrachium.